Engine pressure control



1951 F. w. KERFOOT ENGINE PRESSURE CONTROL 2 Sheets-Sheet 1 Filed June 21, 1946 Aug. 14, 1951 w, KERFOQT 2,563,823

ENGINE PRESSURE CONTROL Filed June 21, 1946 2 Sheets-Sheet 2 Enlsms on.

,fi, ATTORNEY! Patented Aug. 14, 195! ENGINE PRESSURE CONTROL Frank W. Keri'oot, Stamford, Conn., assignor to General Motors Corporation, Detroit, Mich, a

corporation of Delaware Application June 21, 1946, Serial No. 678,510

18 Claims. (01. 123403) This invention relates to manifold pressure regulation for supercharged internal combustion engines such as used on aircraft.

An object of the invention is to provide for the manual control of pressure selection in combination with automatic means under control of altitude-pressure or under control of the temperature of the fuel mixture or under joint control of altitude pressure and fuel mixture temperature for limiting the extent to which engine intake pressure can be raised so that detonation will be avoided. and to provide means for rendering the pressure limiting means non-effective when liquid injection is used to reduce the temperature of the fuel mixture.

A further object of the invention is to provide for intake pressure regulation for an engine having main and auxiliary superchargers, the main supercharger being driven directly by the engine and the auxiliary supercharger operating normally at a minimum speed through a variable speed drive while the main supercharger is capable of supplying the demanded pressure after which the auxiliary supercharger speed is increased in order that demanded pressure may be maintained at altitudes above that which are critical for operation with the main supercharger alone. In the disclosed embodiment of the present invention, the variable speed drive for the auxiliary supercharger is under control by the pressure regulator. The control is such that when critical altitude for main supercharger operation alone is reached, the pressure regulator causes the speed of the auxiliary supercharger to be increased in order to meet the demand for pressure at altitudes above said critical altitude.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Fig. 1 is a perspective view of a pressure regulator unit embodying the present invention.

Figs. 2 and 3 are sectional views taken respectively on the lines 2-2 and 3-3 of Fig. 4.

Fig. 4 includes longitudinal sectional views of the pressure regulator and auxiliary supercharger speed controller and a diagram of connections.

Fig. 5 is a fragmentary view showing parts of the pressure regulator in positions different from those appearing in Fig. 4.

The pressure regulator, shown in Fig. 1, comprises a case ll to which screws Ii secure side cover sections 4 2A and I23 and to which screws l3 2 secure an end cover plate l4. Referring to Fig. 2, it will be seen that case l0 provides bearings ii for a shaft It to which is secured a lever ll to be connected with the engine throttle valve not shown. Shaft I5 is connected also with a lever I8 carrying a roller l9 received in a cam slot 20 of a lever 2| pivotally supported by a pin 22 carried" by a cam plate 23 (Fig. 4) which is attached to a shaft 24 attached to a main control lever 25 which is manually operated. Shaft 24 is journaled in bearings 25 provided by the cover rate I2A. Since the lever 25 (Fig. 1) is used to select the pressure to be maintained by the pressure regulator, the positions of lever 25 may be designated by a scale 21 graduated to reach absolute pressure in inches of mercury.

The selection of pressures by lever 25 is effected -by the cam surface 30 of the plate 23 (Fig. 4). Surface 30 is engaged by a roller 3| carried by lever 32 which is pivotally supported by a screw 33 (Fig. 3) attached to the case Ill. Lever 32 carries a pin 34 pivotally supporting a lever 35 which is urged in a clockwise direction (Fig. 4) by a spring 35 having parts which are coiled around the pin 34 (Fig. 3) and having a bale or yoke 31 bearing against the lever 35 and a yoke 38 bearing against the lever 32. The spring 35 urges a stop screw 39 against a lug 40 of lever 32. The position of screw 39 relative to lever 35 can be locked in adjusted position by a nut 4l'.

Lever 35 carries a pin 42 pivotally connected with a link comprising a portion 43, a turnbuckle 44 and a portion 45 pivotally connected by a pin 46 with a lever 41. A spring 46a connecting pin 45 with the cover I4 urges the levers 41 and 32 counterclockwise. Lever 41 is supported by a pin 48 and connected at its lower end by pin 49 with a valve 50 slidable in a, guide 5| provided by the case l0 and having lands 52 and 53 which control the distribution of pressure oil from an inlet port 54 to outlet ports 55 and 56 connected, respectively, with opposite ends of a cylinder 51 containing a piston 58 connected by rod 59 with a head 50 having a slot 6i receiving a pin 52 carried by the lever 2|. A spring 53 confined between the piston 58 and the cover [4 urges the piston 58 toward the right. The pin 48 which supports lever 41 is carried by a bridge supported by the free ends of metal bellows 66 and 61 whose fixed ends are attached to cover i4 and to a partition 58 provided by the case Ill. The bellows G6 is evacuated. The interior of bellows 51 is in communication with the engine intake by means of a duct 69 within the case It which is connected b pipe 10 exterior to the case ill (Fig. 1) and connected, with the engine intake, not shown. Oil from a pressure source is connected by pipe 'II with the port 54 (Fig. 4). Since the bellows 88 and 81 have equal areas, variations in altitude pressure do not affect the position of the pin 48. Coiled springs, not shown, are located within the bellows 88 and 81 and are so constructed and callbrated that the relation betweenengine intake pressures and positions of the pin 48 is a linear relation. For details of the springs within the bellows reference is made to the copending application of Dolza et a1, Serial No. 449,918, filed July 6, 1942 and now forfeited.

In Fig. 4, the cam plate 28 is shown in position for lowest pressure selection, lever 25 being in the position shown in Fig. 1. Bellows 81 is somewhat collapsed and bellows 88 is somewhat expanded. Valve 58 is located so as to connect ports 54 and 55 thereby admitting pressure fluid to the left of piston 58. Movement of lever 25 counterclockwise into a position for selecting pressure suitable for flight causes the cam plate 23 to move into position for selecting a higher pressure.

, As plate 23 moves counterclockwise it carries with it the pin 22 which supports the lever 2|. Assuming that the pin 82' is restrained by slot 8|, counterclockwise movement of pin 22 causes lever 2| to move clockwise, thereby causing lever I8, shaft I8 and lever I! to move clockwiseto effect an opening movement of the throttle valve in response to movement of the manually operated control lever 25. As cam plate 28 moves counterclockwise, the roller 8| follows the cam due to the action of spring 4811. Valve '58 moves toward the right to connect ports 54 and 58 and to connect port 55 with the interior of the case I8. Admission of pressure oil to the right of piston 58 causes it to move left, thereby moving lever 2| further in a clockwise direction. As lever 2| thus moves, the throttle operating lever I'I moves clockwise to effect what further opening movement of the throttle is required to maintain the selected pressure. Fig. shows the positions of sition 58 (Fig. 4) and causes lever 2| to move into such position that lever I8 moves into position I8 (Fig. 5) ,thereby 'causing the throttle valve to be fully opened. The mechanism is so constructedthat for various positions of lever 25 and cam plate 23 selecting pressures suitable for flight,vthe throttle valve lever II will be moved to throttle wide open position I8 at altitudes which are critical when the engine is being supercharged by the main supercharger alone. More particularly, this is accomplished by the peculiar shape of the cam slot 28 in lever 2|.

In order that selected pressures may be obtained at altitudes above those which are critical when the main supercharger is operating alone, the auxiliary supercharger is caused to operate automatically in a manner such as to increase the supercharging effect. Normally, the I auxiliary supercharger operates at an idling speed such that it will ofler a minimum of resistance to the flow ofair or fuel mixture to the engine. This auxiliary supercharger is not shown inthe drawings but it will be understood that it can be one which is connected with the engine through a variable ratio hydraulic coupling such as disclosed in the copending application of Dolza et al., Serial No. 520,878, filed February 3, 1944, now Patent No. 2,481,482 granted December 20, 1949. This auxiliary supercharger is driven by atubular shaft 88 (Fig. 4) joumaled in a bearing 8| and connected with an hydraulic coupling driven member 82 which cooperates with a driving couplingv member 83 attached to a shaft 84 journaled in the housing of the hydraulic coupling. Shaft 84 is connected with an engine driven shaft not shown. Engine driven oil-pump P forces pressure oil through a pipe 88 to the bearing 8|, and thence it flows to the tubular shaft 88 for the pu pose of filling the coupling members and the shroud 81 which is attached to the coupling member 88. The coupling ratio is determined by the rotative level of fluid within the shroud 81 and within the coupling members 82 and 83. This rotative level is determined by the position of a scoop 88 of tubular construction and having an inlet slot at 88 and an outlet slot at 88 from which oil can escape to a drain through a port 8| of the coupling housing 85. Slot 88 receives the end of a screw 82 which prevents rotation of the scoop 88 as it moves longitudinally in a bearing 83 provided by housing 85. If the scoop 88 is in the position shown, the rotating level of oil in the coupling members will be at a relatively great distance radially from the axis of the coupling; that is, the level will be low and the coupling ratio will be low and the slip percentage will be high. Therefore the shaft 88 will rotate at a low speed relative to the shaft 84. This is the condition for the idling operation of the auxiliary supercharger which therefore does not consume much power while the main supercharger alone is able to supply the demanded intake pressures. When altitudes are reached such that the main supercharger can no longer supply the pressures demanded, the scoop 88 is caused automatically to move toward the left to increase the depth of the oil within the coupling by decreasing the radial distance from the axis of the coupling to the rotative oil level within the coupling. The scoop 88 is moved left by hydraulic pressure. For this purpose, the scoop 88 isconnected with a head of a rivet 84 attached to apiston 85 received by a cylinder 88 attached to the coupling housing 85. The cylinder 88 is attached to a cap 81. A spring 88 is confined between the cap 81 and the piston 85 and urges the piston toward the right. Cap 81 is connected by a pipe 88 with the left end of cylinder 51 of the pressure regulator. Pressure oil is conducted to the right side of piston 85 by passage I88 in a block I8I attached to or integral with cylinder 88. In passage I88 there is located the end of a flow metering screw I82 which can be locked in adjusted position by a nut I83. Passage I88 is connected by pipe I84 with a port I85 in the side of cylinder 51. Port I85 is so located that it will be at the right of piston 58 when the latter has moved into position for effecting full opening of the throttle. When altitudes are reached sufficient that demanded pressure cannot be supplied by the main supercharger alone, the piston 58 will have been moved toward the left past the port I85 so as to open the throttle valve fully.

the demanded pressure is over-supplied, the valve 50 will be moved left so as to connect ports 54 and 55 and to connect port 58 with drain. Therefore the left side of piston 95 will be connected with port 54 while the right side is connected with drain through passage I00, pipe I04, cylinder 51 and port 58. Therefore the scoop 88 will move in to decrease the coupling ratio whereupon the speed of the auxiliary supercharger will decrease so that it. will not operate any faster than necessary to maintain the demanded pressure.- Obviously, as altitude increases, the scoop 88 will move toward the left in order to increase the coupling ratio to its maximum beyond which there can be no further supercharging effect; and an altitude will then have been reached which is critical for operation of both main and auxiliary superchargers.

For rapid acceleration of the speed of the auxiliary supercharger, it may be desirable to increase the rate of filling the hydraulic coupling. This may be accomplished by the use of an additional fluid pressure source such as an accumulator IIO connected by pipe I We with engine oil pressure. A restriction H01) in pipe IIOa prevents appreciable loss of engine oil pressure while filling the accumulator. The accumulator is connected with a valve port III controlled by valve I I2 sliding in a guide I I3 extending from a cylinder II4 containing a piston H5 connected with the valve II2. A spring II8 urges the piston I I5 toward the left in a position which normally closes the port I I2. The left end of cylinder I I4 is connected by pipe I I! with pipe I04 and the right end of cylinder I I4 is connected by pipe 1H8 with passage I00. While the fluid pressures on the opposite ends of the cylinder II4 are substantially equal, the spring I I8 will hold the valve I I2 in the position shown. As a result of a sudden demand for increase in manifold pressure beyond that which can be obtained by the main supercharger alone, the piston 58 moves rapidly to the position 58', thereby opening the port I05 quickly. then pressure on the left side of the piston I I5 will exceed that on the right and the valve II2 will be moved to the right so as to connect accumulator discharge port III with pipe II9 leading to the shaft bearing 8| and thence to the hydraulic coupling.

The deceleration of the auxiliary supercharger may be relatively slow or fast depending on certain conditions. If the pressure-boost by the auxiliary supercharger is slightly in excess of that required to meet the demand when the throttle is wide open, instead of the throttle valve closing to reduce the excess, the scoop 88 may creep to the right. This may occur because the pressure caused by the load of spring 98 on piston 95 is greater than the pressure caused by the load of spring 83 on piston 58. If the excess of boost is such as to require slight closing movement of the throttle valve, the piston 58 will move right temporarily to close port I 05. Piston 95 will creep to the right due to leakage and spring load. If the required closing movement of the throttle is greater, piston 58 will move to the right of port I05 so that the left end of cylinder 51 is connected with pipes 99 and I04, piston 95 will move to the right fairly rapidly as flow through passage I00 is restricted only by metering pin I02.

The pressure regulator is provided with means under the joint control by altitude pressure and by mixture temperature for preventing the attainment of such pressure as would cause englne detonation, although the main control lever 25 might be moved to a position demanding such high pressures. For this purpose the screw 33 (Fig. 3) supports a hub of a lever I20 carrying an adjustable stop screw I2I adapted to engage the lever 32 under certain conditions, thereby preventing the follower roller 3| from following the cam surface 30 into high pressure selecting positions. Lever I20 is connected by a link I22 with a clevis I23 connected by pin I24 with lever I25 connected by a pin I28 with a rod I2'Ia threadedly connected with the free end of an aneroid bellows I21 located in a chamber I28 which can be connected with the airplane air scoop by a pipe I29 (Fig. 1). Therefore the bellows I221 is under control by altitude pressure. For convenience in assembly, the bellows I21 may be mounted on a plug I30 which can be threaded into the bottom wall of the chamber I28.-

Lever I25 carries a pin I3I received by the forked end of a lever I32 journaled on a screw I33 threaded into the case I0, the attachment being made accessible upon the removal of a plug I34. Cover I4 provides a tubular portion I35 engaged by seal rings I38 retained by grooved collars I31 attached to an outer tube I38 whose left end is attached to a ring I39 which is attached to an inner tube I40. A spring I4! urges the ring I39 and hence the tubes I38 and I40 toward the right. The right end of tube I38 strikes against a partition I42, thus sealing that end of said tube. The right end of tube I40 is attached to a plug I43 slidable through a tubular boss I44 of a partition I42 in case I0, said plug I43 having a seal ring I45 received by its annular groove. The right end of plug I43 provides a slot I48 for receiving an arm of the lever I32.

Referring to Fig. l, fuel-air mixture or air is conducted from the engine induction system by a pipe I50 leading through the opening I5I. The mixture flows right through the tube I40, through passages I52 and through the space between the tubes I40 and I38 and out through the passages I53 to a passage I54 connected by a pipe I55 (Fig. l) with the engine intake. The temperature of the tubes I38 and I40 responds to the temperature of the fuel mixture or air being conducted to the engine intake. Tube I38 is made of metal, such as Invar, having relatively low temperature coefficient of expansion and the tube I40 is made of metal, such as aluminum, having a relatively high coefficient. Therefore, there is an appreciable relative movement between the tubes I40 and I38. As tube I38 expands, its right end being fixed, its left end will move slightly toward the left; but, since tube I40 has greater temperature coeflicient of expansion, the right end of tube I40 will move appreciably relative to the right end of tube I38. This movement is transmitted by the lever I32 to the rod I22 and thence to the lever I20. Rod I22 passes through a bracket I having a spring retainer boss I6I upon which is seated a spring I82 pressing up against a spring seat washer I83 attached to the rod I22. The spring I82 urges the lever I 25 counterclockwise and lever I32 clockwise. Hence lever I32 is maintained in engagement with the right wall of slot I48 of block I43.

As mixture temperature increases, block I43 moves toward the right and the lever I32 follows along due to the action of spring I82. Therefore lever I20 moves clockwise and the stop screw I2I moves toward lever 32, thereby limiting the extent to which the lever 32 can move counterclockwise whereby the extent to which the roller 3I can follow the cam surface 30 is limited. Like- ,such movement of lever 32.

wise, as altitude pressure decreases, bellows I21 expands, thereby moving lever I25 clockwise relative to its pivot I3I, thereby raising the rod I22 and causing lever I20 to move clockwise. Thus the stop screw I2I is under joint control by mixture temperature responsive means and by altitude pressure responsive means whereby lever 32 is prevented from moving into such position of pressure selection as would cause the engine to detonate.

On a warm day the pressure selection would be less than on a cold day; and, at a higher altitude, the pressure selection would be less than at a lower altitude. Although the altitude responsive means does move more or less slowly. depending on how fast the altitude changes,

.alone it has no control over detonation. Detonarect efiect of altitude on detonation is through reduction of exhaust back pressure with increase in altitude. Thus at a given fuel-air mixture temperature the efiect of a lower exhaust back pressure is to reduce the detonation limit (1. e. manifold pressure at which incipient detonation occurs) This effect of exhaust back pressure on the detonation limit is slight at low altitude; the eifect increases as altitude increases until it is very apparent near the critical altitude.

Whereas the engine will detonate at certain pressures when mixture temperature exceeds a certain amount or when pressure altitude exceeds a certain amount, the engine will operate without detonation at these same pressures provided liquid injection is used for cooling the mixture by spraying into the mixture conduit a jet of alcohol water mixture. The means for supplying alcohol water mixture under pressure to a spray nozzle is caused to operate a fluid pressure responsive means for retracting the lever I20 in'a counterclockwise direction from lever 32 so that the pressure limiting means is rendered non-effective. For this purpose the right wall or the case I is provided with an opening I10 closed by a diaphragm III which serves also as a gasket between a cap I12 and the outer wall of the case III. The.

chamber I13 between the cap I12 and the diaphragm "I is connected by a pipe I14 with the alcohol-water pressure source. When this pressure is strong enough to overcome the spring I62, the diaphragm HI and the rod Illa connecting it with lever I20 will move toward the left, thereby causing lever I20 to move counterclockwise to move the stop screw I2I far enough away from the lever 32 to permit obtaining the highest pressure of which the apparatus is capable of selection. Fig. 5 shows cam plate 23 in the position of highest pressure selection and the roller 3I is still following the cam surface 30 since screw I2I has moved far enough to the left to permit As rod I22 moves down under the action of fluid pressure against the right of diaphragm I1 I, lever I25 moves clockwise and lever I32 moves counterclockwise, said movement of the latter being unobstructed since the slot I46 is wide enough to permit movement of lever I32 counterclockwise, although the plug gine comprising a member for actuating a throt- I43 may not move. Spring I62 should be stronger than spring 46a so as to prevent counterclockwise movement of lever 32 after it engages stop screw I2I but spring I62 should be weak enough to be overcome by the minimum fluid (alcoholwater) pressure acting on the diaphragm I1I.

From the foregoing description, it is apparent that the present invention provides for sequential operation of the engine throttle valve and the hydraulic coupling scoop. The pressure regulator causes the throttle valve to open wide at critical altitude for operation with the enginestage supercharger. Then the scoop moves to increase the speed of the auxiliary supercharger. If the intake pressure exceeds the demand, the throttle valve closes and then the scoop moves to decrease supercharger speed to reduc the pressure excess. The invention provides for enclosure of movable parts except for the main control lever and the throttle operating lever. At critical altitude, the throttle valve is substantially wide open when the pressure selections range from those required for cruising up to maximum. Adjustments of lengths of upper arm of lever 32 and of link 43445 and the location of stop screw I2I can be made while the level of the oil submerging the bellows 66-61 is up to the top of partition 68. Such adjustments are accessible by movement of the upper side-cover I 2B. The invention provides means for limiting obtainable pressures to values such that the engine does not detonate when running dry (without liquid injection), said means being under joint control by altitude and by mixture temperature. The said limiting means is overridden (rendered non-effective), when an antidetonant (alcohol-water spray) is used.

While the embodiment of the present inventionas herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

Whatis claimed is as follows:

1. Apparatus 'for controlling the intake pressure of a supercharged internal combustion engine comprising a member for actuating a throttle valve in the engine induction passage, a servomotor for operating said member, a device responsive to altitude pressure, a device responsive to the temperature of the engine operating medium, a manually positioned part, pressure selecting means under control by said devices and part, an element responsive to engine intake pressure and means under control by the pressure selecting means and by the element for controlling the servomotor.

2. Apparatus for controlling the intake pressure of a supercharged internal combustion engine comprising a member for actuating s, throttle valve in the engine induction passage, a servomotor for operating said member, a device responsive to altitude pressure, a device responsive to the temperature of the engine operating medium, a device responsive to the attainment of a certain pressure of a liquid inj cted into the engine induction passage, a manually positioned part, pressure selecting means under control by said devices and part, an element responsive to engine intake pressure and means under control by the pressure selecting means and by the element for controlling the servomotor.

.3. Apparatus for controlling the intake pressure of a supercharged internal combustion entle valve in the engine induction passage, a

servomotor for operating said member, a device responsive to altitude pressure, a device responsive to the temperature oi! the engine operating medium, an element responsive to engine intake pressure, a manually operable part, pressure selecting means operated by said part, means under joint control by said devices for modifying the action or the pressure selecting means so as to limit the obtainable pressure to a value less than can be demanded by manual operation, and means under control by said element and by said pressure selecting means for controllin the servomotor.

4. Apparatus for controlling the intake pressure of a supercharged internal combustion engine comprising a member for actuating a throttle valve in the engine induction passage, a servomotor for operating said member, a device responsive to altitude pressure, a device responsive to the temperature of the engine operating medium, an element responsive to engine intake pressure, a manually operable part, pressure selecting means operated by said part, means under joint control by said devices for moditying the action of the pressure selecting means so as to limit the obtainable pressure to a value less than can be demanded by manual operation, a third device responsive to the attainment of a certain pressure of a liquid injected into the engine induction passage for nullifying the modifyin action of the two devices first mentioned, and means under control by said element and by said pressure selecting means for controlling the servomotor.

5. Apparatus for controlling the intake pressure of a supercharged internal combustion engine comprising a member for actuating a throttle valve in the engine induction passage, a servomotor for operating said member, a manually adjusted pressure selecting cam, a cam follower engageable with the cam, an element responsive to engine intake pressure, means under joint control by the element and the cam follower for controlling the servomotor, a stop for limiting the extent to which the cam follower can follow the cam, a device responsive to altitude pressure, a device responsive to the temperature of the engine operating medium and means under joint control by the device for positioning the stop.

6. Apparatus for controlling the intake pressure of a supercharged internal combustion engine comprising a member for actuating a throttle valve in the engine induction passage, a servomotor for operatingsaid member, a manually adjusted pressure selecting cam, a cam follower engageable with the cam, an element responsive to engine intake pressure, means under joint control by the element and the cam follower for controlling the servomotor, a stop for limiting the extent to which the cam follower can follow the cam, a device responsive to altitude pressure,

sive to the attainment 01' a certain pressure or a liquid injected into the engine induction passage, a manually positioned part, pressure selecting means under control by said devices and part, an element responsive to engine intake pressure and means under control by the pressure selecting means and by the element for controlling the servomotor.

8. Apparatus for controlling the intake pressure of a supercharged lntemal combustion engine comprising a member for actuating a throttle valve in the engine induction passage, a servomotor for operating said member, a device responsive to altitude pressure, an element responsive to engine intake pressure, a manually operable part, pressure selecting means operated by said part, means controlled by said device for modifying the action of the pressure selecting means so as to limit the obtainable pressure to a value less than can be demanded by manual operation, a second device responsive to the attainment of a certain pressure of liquid injected into the engine induction passage for nullifying the modifying action of the device first mentioned, and means under control by said element and by said pressure selecting means for controlling the servomotor.

9. Apparatus for controlling the intake pressure of a supercharged internal combustion engine comprising a member for actuating a throttle valve in the engine induction passage, a servomotor for operating said member, a manually adjusted pressure selecting cam, a cam follower engageable with the cam, an element responsive to engine intake pressure, means under joint control by the element and the cam follower for controlling the servomotor, a stop for limiting the extent to which the cam follower can follow the cam, a device responsive to altitude pressure for positioning the stop, and means including a diaphragm operable to position the stop independently of the device when the pressure of an injection fluid attains a certain value.

10. Apparatus for controlling the intake pressure of a supercharged internal combustion engine comprising a member for actuating a throttle valve in the engine induction passage, 9.

servomotor for operating said member, a deviceresponsive to the temperature of the engine operating medium, a device responsive to the attainment of a certain pressure of a liquid injected into the engine induction passage, a manually positioned part, pressure selecting means under control by said devices and part, an element responsive to engine intake pressure and means under control by the pressure selecting means and by the element for controlling the servomotor.

ll. Apparatus for controlling the intake pressure of a supercharged internal combustion engine comprising a member for actuating a throttle valve in the engine induction passage, a servomotor for operating said member, a device responsive to the temperature of the engine operating medium, an element responsive to engine intake pressure, a manually operable part, pressure selecting means operated by said part, means controlled by said device for modifying the action of the pressure selecting means so as to limit the obtainable pressure to a. value less than can be demanded by manual operation, and a second device responsive to the attainment of a certain pressure of liquid injected into the engine induction passage for nullifying the modifying action of the device first mentioned,

aoeaoaa and means under control by said element and by said pressure selecting means for controlling the servomotor.

12. Apparatus for controlling the intake pressure of a supercharged internal combustion engine comprising a member for actuating a throttle valve in the engine induction passage, a servomotor for operating said member, a manually adjusted pressure selecting cam, a cam follower engageable with the cam, an element responsive to engine intake pressure, means under joint control by the element and the cam follower for controlling the servomotor, a stop for limiting the extent to which the cam follower can follow the cam, a device responsive to the temperature of the engine operating medium for positioning the stop, and means including a diaphragm operable to position the stop independently of the device when the pressure of an injection fluid attains a certain value.

13. Apparatus for controlling the intake pressure of a supercharged internal combustion engine comprising a member for actuating a throttle valve in the engine induction passage, an hydraulic servomotor for operating said member, a pressure selecting device, an element responsive to engine intake pressure, means under control by the device and element for controlling the servomotor so that it'will so position the throttle valve as to maintain a selected pressure, a movable part for controlling the speed ratio of a transmission between the engine and a supercharger, an hydraulic servomotor for operating said part, and means whereby the second mentionedservomotor is caused to receive fluid under pressure in response to a predetermined operation of the flrst servomotor, and thereby to effect the increase of supercharger speed upon the movement of the throttle valve to a certain open position.

14. Apparatus for controlling the intake pressure of a supercharged internal combustion en- 12 der of the first servomotor with that end of the cylinder of the other servomotor away from which the piston of said other servomotor moves when operating to increase the speed ratio oi the transmission.

16. Apparatus according to claim 14 further characterized by the inclusion of springs located respectively in the cylinders of the servomotors, one spring operating to resist movement of the piston of the first servomotor in the throttlevalve-opening direction, the other spring operating to resist movement of the piston oi the second servomotor in the transmission-speed-ratioincreasing direction.

17. Apparatus according to claim 14 further characterized by the inclusion of springs located respectively in the cylinders 01' the servomotors, one spring operating to resist movement of the piston of the first servomotor in the throttlevalve-opening direction, the other spring operating to resist movement of the piston of the second servomotor in the transmission-speed-ratioincreasing direction and by the inclusion of a flow metering valve in the duct which connects the cylinder of the first servomotor with that end of the cylinder of the other servomotor away from the piston of said other servomotor moves gine comprising a member for actuating a throt- 1 tle valve in the engine induction passage,.an hydraulic servomotor comprising a cylinder and a piston within the cylinder and connected with said member, a valve for controlling the distribution of pressure fluid to the ends of the cylinder, a pressure selecting device, an element responsive to engine intake pressure, means under control by the device and element for controlling the valve of the servomotor so that the servomotor will so position the throttle valve as to maintain aselected pressure, a movable part for'controlling the speed ratio of a transmission between the engine and a suprcharger, a second hydraulic servomotor comprising a cylinder and a piston therein and connected with said part. and ducts respectively connecting the ends of the cylinders of the hydraulic motors. said ducts providing ports in the cylinder of the first hydraulic motor which are controlled by thepiston thereof. 4

15. Apparatus according to claim 14 further characterized by the inclusion 01' a flow metering valve in the duct which connects the cylin when operating to increase the speed ratio of the transmission.

18. Apparatus according to claim 14 further characterized by the fact that the part operated by the second servomotor controls the rotative oil level in an hydraulic fluid coupling drive which provides the variable speed-ratio transmission between the engineand a supercharger and further characterized by the inclusion of a flow metering valve in the duct which connects thecylinder of the firstservomotor with that end of the cylinder of the other servomotor away from which the piston 01' said other "servomotor moveswhen operating to increase the'speed ratio 01' the transmission, and further characterized by the provision of means responsive to the attainment of a predetermined pressure drop across the flow metering valve for eflecting an accelerated filling of the fluid coupling.

FRANK W. KERFOO'I'.

' REFERENCES crrnn The following; references are of record in the file of this patent:

UNITED STATES PATENTS I 

